When comparing Steel Bank Common Lisp (SBCL) vs MIT/GNU, the Slant community recommends Steel Bank Common Lisp (SBCL) for most people. In the question“What are the best Lisp dialects?”Steel Bank Common Lisp (SBCL) is ranked 5th while MIT/GNU is ranked 8th. The most important reason people chose Steel Bank Common Lisp (SBCL) is:

Parts of SBCL are licensed under a BSD-Style license. The rest are in the public domain.